Rome, Italy (CNN)Pope Francis has accepted the resignation of Cardinal Theodore McCarrick, who once led the Archdiocese of Washington and was a force in American politics, after a decades-old allegation of sexual abuse of a teenage altar boy forced the Vatican to remove him from public ministry. McCarrick, 88, was informed several months ago that the Archdiocese of New York, where he was ordained in 1958, was investigating an allegation of abuse from a teenager “from almost fifty years ago,” McCarrick said in June, when the Pope ordered him to…